Repairing defective pixels

1. An apparatus, comprising: pixel defect logic configured to retrieve pixel repair information that comprises locations of defective photo sensors in an array of photo sensors; pixel replication logic configured to repair defective pixels generated by the array of photo sensors by identifying the defective pixels based on the locations of defective photo sensors where the defective pixels are repaired in a stream of image pixels based, at least in part, on the pixel repair information comprising filtering information; and point defect logic configured to identify a point defect pixel in the stream of image pixels after the pixel repair information is applied, wherein a point defect pixel is a pixel in the stream of image pixels that is not repairable by the pixel replication logic using the pixel repair information; and wherein the point defect logic is configured to adjust the point defect pixel by applying a two-dimensional filter based, at least in part, on a two dimensional array of values from pixels adjacent to the point defect pixel.

2. The apparatus of claim 1 , where the pixel replication logic comprises: a delay line for storing pixels from the stream of image pixels in a group of delay elements, where the pixel replication logic functions to repair defective pixels in a replication window of pixels as the stream of image pixels is shifted through the group of delay elements.

3. The apparatus of claim 1 , wherein the pixel repair information includes predetermined repair instructions for repairing two or more pixels in the stream of image pixels, wherein the predetermined repair instructions are associated with a predetermined location corresponding to a location of a defective photo sensor; and where the pixel replication logic is configured to repair a defective pixel that matches the predetermined location in accordance with the corresponding predetermined instructions.

4. The apparatus of claim 1 , where the pixel replication logic is configured to provide a pixel address to the pixel defect logic, and where the pixel defect logic functions to provide repair information to the pixel replication logic when the pixel address matches a location of a defective photo sensor from the pixel repair information.

5. The apparatus of claim 1 , where the pixel defect logic is configured to provide a correction field to the pixel replication logic, and where the pixel replication logic functions to repair defective pixels based, at least in part, on the correction field.

6. The apparatus of claim 1 , where the pixel replication logic further comprises: a string of delay elements to sequentially shift the stream of image pixels, where a replication window of pixels is a string of adjacent back-to-back pixels in the string of delay elements, and where the pixel replication logic functions to repair defective pixels in the replication window of pixels as the stream of image pixels is sequentially shifted through the string of delay elements.

7. The apparatus of claim 6 , where the pixel replication logic is configured to repair defective pixels in the replication window when a pixel address of a pixel in the replication window is equal to a pixel repair address in the pixel defect logic.

8. The apparatus of claim 6 , where the pixel repair information provides information on how to repair one or more of the pixels in the replication window.

9. The apparatus of claim 1 , wherein the pixel repair information includes predetermined repair instructions for repairing two or more pixels in a cluster of pixels based on a sequence of non-defective pixels and defective pixels in the cluster based on the locations of defective photo sensors of the array of photo sensors.

10. An apparatus, comprising: pixel replication logic configured to repair defective pixels generated by an array of photo sensors wherein the defective pixels are identified based on stored locations of defective photo sensors, wherein the defective pixels are repaired in a pixel cluster based, at least in part, on pixel repair instructions that are predefined for the defective photo sensors and for types of pixel clusters; point defect logic configured to detect a point defect pixel in the pixel cluster after the pixel repair instructions are performed, where a point defect pixel is a pixel in the pixel cluster that is not repairable with the pixel repair instructions; and a two-dimensional filter configured to adjust the point defect pixel based, at least in part, on a two dimensional array of values from pixels adjacent to the point defect pixel.

11. The apparatus of claim 10 , where the two-dimensional filter functions to: calculate a local mean of the point defect pixel based, at least in part, on adjacent pixels associated with the same color as the point defect pixel; calculate a local variance of the point defect pixel based, at least in part, on the adjacent pixels associated with the same color and the local mean; determine whether the point defect pixel is repairable based, at least in part, on the local mean and the local variance; and filter the point defect pixel with a two-dimensional median filter when the point defect pixel is repairable.

12. The apparatus of claim 11 , where the apparatus is configured to repair the point defect pixel if the local variance is greater than or equal to a pixel variance value.

13. A method, comprising: for a pixel cluster of two or more adjacent pixels of a sequential string of pixels, determining addresses of the pixel cluster and based on the addresses, determining a cluster type of the pixel cluster; wherein the cluster type is based on a sequence of non-defective pixels and defective pixels of the pixels in the pixel cluster that is predetermined from locations of known defective photo sensors in an array of photo sensors used to generate the sequential string of pixels; repairing two or more of the defective pixels in the pixel cluster based, at least in part, on the cluster type using at least predetermined repair instructions that are defined for the cluster type; and after repairing two or more of the defective pixels in the pixel cluster using the predetermined repair instructions: identifying a point defect pixel in the pixel cluster that is not repairable based, at least in part, on the predetermined repair instructions; determining whether the point defect pixel is adjustable; and adjusting the point defect pixel when the point defect pixel is adjustable by filtering the point defect pixel in two directions.

14. The method of claim 13 , comprising: shifting the pixel cluster into a delay line one pixel at a time, where the pixel cluster is a sequential line of pixels with two ends, where the delay line stores the pixel cluster and one or more pixels adjacent to both of the two ends, and where repairing at least some of the defective pixels is performed based, at least in part, on the pixel cluster and the one or more pixels adjacent to the two ends.

15. The method of claim 13 , where repairing at least some of the defective pixels is performed by replacing a defective pixel with an adjacent pixel associated with the same color or by replacing a defective pixel with an average of two adjacent pixels associated with the same color.

16. The method of claim 13 , wherein adjusting the point defect pixel comprises: calculating a local mean of the point defect pixel based, at least in part, on adjacent pixels associated with a same color as the point defect pixel; calculating a local variance of the point defect pixel based, at least in part, on adjacent pixels associated with the same color as the point defect pixel and based, at least in part, on the local mean; determining if the point defect pixel is adjustable based, at least in part, on the local mean and the local variance; and adjusting the point defect pixel when the point defect pixel is adjustable by filtering the point defect pixel.

17. The method of claim 13 , comprising: comparing a cluster address associated with the pixel cluster with a type address used to retrieve the cluster type to determine when the cluster address and the type address are the same; and retrieving the cluster type when the cluster address and the type address are the same.

18. The method of claim 13 , where repairing two or more of the defective pixels is based, at least in part, on positions of defective pixels and non-defective pixels in the pixel cluster.